Method and Device for Producing an Opening from a Motherbore and into a Formation

ABSTRACT

A method and device for producing an opening from a motherbore into the surrounding formation, wherein the method includes: positioning a motor, having a rotatable barrel, in the motherbore; passing an elongated body through the barrel; and letting the motor rotate the elongated body as the elongated body is moved along the barrel and into the formation.

FIELD

There is provided a method for producing an opening from a motherbore and into a formation. The invention also includes a device for practising the method.

BACKGROUND

It is often desirable to have one or more openings extending from a motherbore and into a surrounding formation. According to prior art, such openings that often extend from a motherbore tubular and to in the motherbore, are made for instance by such methods as detonation of a pyrotechnical charge, water or acid jetting.

The purpose of making such openings may be related to production issues or placing of instruments at a distance from the motherbore.

Present techniques for the purpose are relatively inefficient and also somewhat inaccurate in that the reached end position of an opening may be at a distance from the desired position.

SUMMARY

The purpose of the invention is to overcome or reduce at lest one of the disadvantages of the prior art.

The purpose is according to the invention achieved by the features as disclosed in the description below and in the following patent claims.

There is provided a method for producing an opening from a motherbore into the surrounding formation, wherein the method includes:

-   -   positioning a motor, having a rotatable barrel, in the         motherbore;     -   passing an elongated body through the barrel; and letting the         motor rotate the elongated body as the elongated body is moved         along the barrel and into the formation.

The elongated body may be a rod, a tubular or combinations thereof of any kind having sufficient elasticity.

By positioning the motor in the motherbore, a rotational motion may be applied to the elongated body locally. As the motor rotates the elongated body, the elongated body is moved into the formation for instance by use of hydraulic pressure or a feed apparatus of known design.

The method may include positioning the rotatable barrel at a rotational axis of the motor. Thus a compact motor may be designed for the purpose.

The method may further include positioning a guide for the elongated body at least at one end party of the barrel. By utilizing a guide, the elongated body may be directed in the desired direction and hydraulically separated from say the inside of the motherbore tubular. The guide may, if desirable, be positioned wholly outside the motherbore tubular.

The method may further include giving at least a part of the barrel a non-circular cross section, and giving the elongated body a corresponding cross section.

Thus a simple way of transferring rotational torque from the motor and to the elongated body is provided. The cross section may be symmetrical, for instance in the form of a hexagon, or non-symmetrical by for instance providing the barrel or elongated body with a complementary fitting ridge or groove.

The method may further include positioning the motor at least partly outside a motherbore tubular. Further, the motor may be positioned at least partly inside a motherbore tubular or at the leading end party of a motherbore tubular.

The method may further include choosing the motor from a group including electric, hydrostatic and hydrodynamic motors. The motor may be of any suitable kind. The motor may be working singularly or more than one motor in a group along the elongated tubular. An electric motor may be of the step-motor, AC- or DC-motor type. A hydrostatic motor may be a piston- rotation- or progressive cavity type, while a hydro-dynamic motor may be of the turbine type. Energy supply may in the traditional way come from the surface. Local energy sources such as from fluid pressure differences may be utilized.

The method may further include connecting a bit to the leading end party of the elongated body. When the elongated body consists of a tubular also jetting equipment may be connected to the leading end party. In some cases it is practical to attach instruments to the leading end party of the elongated body.

There is also provided a device for producing an opening from a motherbore and into the surrounding formation including:

-   -   a motor that is positioned in motherbore, the motor having a         rotatable barrel;     -   an elongated body that passes through the barrel and is         directable into the formation.

The rotatable barrel may be positioned at a rotational axis of the motor. Other positions may be at a geared position beside the motor.

A guide for the elongated body may be positioned at least at one end party of the barrel. The guide may pass through a motherbore tubular.

At least a part of the rotatable barrel may be non-circular in cross section while the elongated body has a complementary fitting cross section. The elongated body may thus have a symmetrical cross section or a non-symmetrical cross section. It should be noted that the term “non-circular cross section” includes a partly circular cross sections.

The motor may be positioned at least partly outside a mother-bore tubular. It may also be positioned partly on the inside of the motherbore tubular or at the leading end party of a motherbore tubular.

As stated above, a bit or other equipment for making an opening may be connected to the leading end party of the elongated body.

In some cases it may be desirable to install the invention inside an already existing wellbore tubular. It will then be desirable to avoid obstructions for later access. The device may then mainly consist of acid or alcaline soluble materials such as aluminium. In such cases both the motherbore tubular and the formation are penetrated by the bit on the elongated body.

The method and device according to the invention makes it possible to attach a motor locally to a rotating elongated body in a motherbore. This feature makes it possible to overcome a long felt problem of lack of efficiency and accuracy during production of openings from the motherbore, typically a motherbore tubular, and into the formation.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of a preferred method and device is explained under reference to the enclosed drawings, where:

FIG. 1 shows a sketch of a device according to the invention positioned in a motherbore;

FIG. 2 shows an alternative embodiment of the invention shown in FIG. 1;

FIG. 3 shows to a larger scale a section I-I in FIG. 1; and

FIG. 4 shows to a larger scale a section of a non-symmetric elongated element.

DETAILED DESCRIPTION OF THE DRAWINGS

On the drawings the reference number 1 denotes a motherbore that is drilled in a formation 2. A motherbore tubular 4 is placed in the motherbore 1.

A motor 6 is fixed to the outside of the motherbore tubular 1 and covered by a cover 8. The motor 6 is equipped with a rotatable barrel 10 that in this preferred embodiment is rotatable about a rotational axis 12 of the motor 6.

A first guide 14 extends from the barrel's 10 lower end party 16 and curves through the motherbore tubular 4. A second guide 18 extends from the barrel's 10 upper end party 20 and into the motherbore tubular 4.

An elongated body 22, here in the form of a tubular, extends from inside the motherbore tubular 4, through the second guide 18, the barrel 10 of the motor 6, the first guide 14 and into the formation 2. At its leading end party the elongated body 22 has a bit 24.

The barrel 10 that constitutes the driven part of the motor 6, has a hexagon 26 inside cross section, see FIG. 3. The elongated body 22 has a complementary fitting cross section.

When the motor 6 is operating, the barrel 10 rotates. The torque from the barrel 10 is transferred via the hexagon 26 to the elongated body 22 that rotates with the barrel 10. An axial force, here originating from hydraulic pressure in the motherbore tubular 4, forces the elongated body 22 with the bit 24 into the formation 2 thus producing an opening 28.

In FIG. 2 an alternative embodiment is shown. Here the motor 6 and a third guide 30 is connected to a base 32 that locate on a stopper 34 inside the motherbore tubular 4. When in position, the third guide 30 corresponds to a wall bore 36 in the motherbore tubular 4 where through the bit 24 and elongated body 22 is passed through during operation.

Thus the device shown in this embodiment may be utilized at different positions in the motherbore tubular 4.

An example of a non-symmetric cross section 38 of the elongated body 22 is shown in FIG. 4. 

1. A method for producing an opening from a motherbore into the surrounding formation, wherein the method comprises: positioning a motor, having a rotatable barrel, in the motherbore; passing an elongated body through the barrel; and letting the motor rotate the elongated body as the elongated body is moved along the barrel and into the formation.
 2. A method according to claim 1, wherein method comprises positioning the rotatable barrel at a rotational axis of the motor.
 3. A method according to claim 1, wherein the method further comprises positioning a first, second or third guide for the elongated body at least at a first or second end party of the barrel.
 4. A method according to claim 1, wherein the method further comprises giving at least a part of the barrel a noncircular cross section, and giving the elongated body a corresponding cross section.
 5. A method according to claim 1, wherein the method further comprises positioning the motor at least partly outside a motherbore tubular.
 6. A method according to claim 1, wherein the method further comprises positioning the motor at least partly inside a motherbore tubular.
 7. A method according to claim 1, wherein the method further comprises positioning the motor at the leading end party of a motherbore tubular.
 8. A method according to claim 1, wherein the method further comprises choosing the motor from a group including electric, hydrostatic and hydrodynamic motors.
 9. A method according to claim 1, wherein the method further comprises connecting a bit to the leading end party of the elongated body.
 10. A device for producing an opening from a motherbore into the surrounding formation comprising: a motor that is positioned in the motherbore, the motor having a rotatable barrel; an elongated body that passes through the barrel and is directable into the formation.
 11. A device according to claim 10, wherein the rotatable barrel is positioned at a rotational axis of the motor.
 12. A device according to claim 10, wherein a first, second or third guide for the elongated body is positioned at least at a first or second end party of the barrel.
 13. A device according to claim 10, wherein at least a part of the rotatable barrel is non-circular and where the elongated body has a complementary cross section.
 14. A device according to claim 10, wherein the motor is positioned at least partly outside a motherbore tubular.
 15. A device according to claim 10, wherein the motor is positioned at least partly inside a motherbore tubular.
 16. A device according to claim 10, wherein the motor is positioned at the leading end party of a motherbore tubular.
 17. A device according to claim 10, wherein the motor is chosen from a group including electric, hydrostatic and hydrodynamic motors.
 18. A device according to claim 11, wherein the guide passes through a motherbore tubular.
 19. A device according to claim 10 wherein the elongated body has a symmetrical cross section.
 20. A device according to claim 10 wherein the elongated body has a non-symmetrical cross section.
 21. A device according to claim 10, wherein a bit is connected to the leading end party of the elongated body.
 22. A device according to claim 10, wherein the device mainly consists of acid or alcaline soluble material. 